Dear Simulia,
I am doing research for modelling nonlinear soil reactions for jacket founded offshore wind turbine. It is in combination with using Substructures for the foundation model (soil+piles) called a Seismic Superelement (SSE).
I have trouble getting the same steady state response from both the Complete model (FE Z100 model) and the model that includes a Substructure (SSE model Z103, with Substructure Z103).
I am using a simplified model, it includes two parts:
1 Substructure
-beam
-springs (soil) in two directions
2 Another structure
-beam
The two parts are coupled using a kinematic coupling.
Substructure Z103: For generating the substructure I am using a frequency step to not only get the Guyan modes, but also vibrational modes. I am using a direct steady-state to see if the two models are the same.
The end parts of the springs are supposed to be available for displacement loading (for simulating earth motions).
Right now I have restrained the retained DOFs to zero displacement for the Direct Steady-State plot and for the Frequency Analysis. I am uncertain about the setup of the Boundary Conditions in the Substructure to carry over the proper information (vibrational modes etc.). However, I expected the frequency response to be the same with the current setup.
I have added the results for the Direct Steady-state for the Top Node of Part 2 in Excel. It can be seen that they are not equal.
Can you please help me understand why there is a difference and how/if I can make them equal again?
Kind regards,
Martin Dirkzwager
Abaqus